Xenix.
Xenix was actually licensed by Microsoft from AT&T in 1979. It was the exact same bog standard PDP11 Version 7 Unix that I had access to at UCB. Microsoft never actually coded anything[0] for Xenix, rather they sub-licensed the AT&T source code to third parties, who did the actual coding and porting.
For example, it was SCO who ported it to the IBM PC's 8086/8088 architecture in roughly 1983. Yes, the very same machine that shipped with MS-DOS. Most of us yawned[1] ... although looking back, it was a pretty good hack by SCO![2] Hindsight's 20/20 ...
The name Xenix came about because Ma Bell couldn't (or didn't want to) let them use the UNIX name. The claim for jealousy guarding the trademarked UNIX name was because MaBell was regulated and wasn't allowed to get into the retail trade, although that always rang a trifle hollow to me.
Before SCO's port was released, there was a TRS-68000 version, a Zilog Z8001 port, and an Altos 8086 version (not necessarily in that order, my mind is concatenating time). There were several others. Microsoft didn't write any of them, rather the third-party companies in question did the coding.
A version of SCO Xenix is available for the download here: ftp://www.tuhs.org/UnixArchive/Distributions/Other/Xenix/ ... Don't blame me for the www in that URL.
[0] Unless you consider adding Redmond copyright crap to a few header files "coding".
[1] Those of us working on BSD at the time looked on Xenix as BSD's somewhat insane & slightly neurotic little brother.
[2] Last time I posted something along these lines, I asked if anyone could remember who ported Xenix to Apple's Lisa. Turns out it was SCO ... I have a copy, my Lisa looks a lot happier running a un*x than the OS she came with. (Don't worry, all you purists, I have the stock software for her, too.)
Biting the hand that feeds IT
